In LTE (Long Term Evolution) systems, the introduction of CA function has been considered. As disclosed in NPL 1, the CA function indicates a function of multiplexing a plurality of carriers (Component Carriers) to be used for communication, thereby improving a communication speed between a base station (eNB: evolved Node B) and a mobile station (UE: User Equipment).
Further, in Group 2 of RAN Working Group which is one of standards bodies participating in 3GPP (3rd Generation Partnership Project), it has been considered that broadcast information, which is a part of control information for communication using a sub-carrier (SCC: Secondary Component Carrier), is notified with being included in an RRC (Radio Resource Control) message transmitted on a main carrier (PCC: Primary Component Carrier). Note that NPL 2 defines the specification of RRC protocol, and NPL 3 defines the specification of X2-AP (X2 Application Protocol). The term “X2” means an interface (transmission path) between eNBs.